net: add skb_checksum_setup
This patch adds a function to set up the partial checksum offset for IP packets (and optionally re-calculate the pseudo-header checksum) into the core network code. The implementation was previously private and duplicated between xen-netback and xen-netfront, however it is not xen-specific and is potentially useful to any network driver. Signed-off-by: Paul Durrant <paul.durrant@citrix.com> Cc: David Miller <davem@davemloft.net> Cc: Eric Dumazet <edumazet@google.com> Cc: Veaceslav Falico <vfalico@redhat.com> Cc: Alexander Duyck <alexander.h.duyck@intel.com> Cc: Nicolas Dichtel <nicolas.dichtel@6wind.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Paul Durrant
David S. Miller
parent
b86f81cca9
commit
ed1f50c3a7
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@ -2893,6 +2893,8 @@ static inline void skb_checksum_none_assert(const struct sk_buff *skb)
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bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off);
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int skb_checksum_setup(struct sk_buff *skb, bool recalculate);
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u32 __skb_get_poff(const struct sk_buff *skb);
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/**
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@ -65,6 +65,7 @@
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#include <net/dst.h>
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#include <net/sock.h>
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#include <net/checksum.h>
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#include <net/ip6_checksum.h>
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#include <net/xfrm.h>
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#include <asm/uaccess.h>
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@ -3549,6 +3550,278 @@ bool skb_partial_csum_set(struct sk_buff *skb, u16 start, u16 off)
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}
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EXPORT_SYMBOL_GPL(skb_partial_csum_set);
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static int skb_maybe_pull_tail(struct sk_buff *skb, unsigned int len,
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unsigned int max)
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{
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if (skb_headlen(skb) >= len)
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return 0;
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/* If we need to pullup then pullup to the max, so we
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* won't need to do it again.
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*/
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if (max > skb->len)
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max = skb->len;
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if (__pskb_pull_tail(skb, max - skb_headlen(skb)) == NULL)
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return -ENOMEM;
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if (skb_headlen(skb) < len)
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return -EPROTO;
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return 0;
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}
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/* This value should be large enough to cover a tagged ethernet header plus
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* maximally sized IP and TCP or UDP headers.
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*/
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#define MAX_IP_HDR_LEN 128
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static int skb_checksum_setup_ip(struct sk_buff *skb, bool recalculate)
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{
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unsigned int off;
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bool fragment;
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int err;
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fragment = false;
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err = skb_maybe_pull_tail(skb,
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sizeof(struct iphdr),
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MAX_IP_HDR_LEN);
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if (err < 0)
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goto out;
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if (ip_hdr(skb)->frag_off & htons(IP_OFFSET | IP_MF))
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fragment = true;
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off = ip_hdrlen(skb);
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err = -EPROTO;
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if (fragment)
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goto out;
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switch (ip_hdr(skb)->protocol) {
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case IPPROTO_TCP:
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err = skb_maybe_pull_tail(skb,
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off + sizeof(struct tcphdr),
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MAX_IP_HDR_LEN);
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if (err < 0)
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goto out;
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if (!skb_partial_csum_set(skb, off,
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offsetof(struct tcphdr, check))) {
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err = -EPROTO;
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goto out;
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}
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if (recalculate)
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tcp_hdr(skb)->check =
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~csum_tcpudp_magic(ip_hdr(skb)->saddr,
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ip_hdr(skb)->daddr,
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skb->len - off,
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IPPROTO_TCP, 0);
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break;
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case IPPROTO_UDP:
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err = skb_maybe_pull_tail(skb,
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off + sizeof(struct udphdr),
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MAX_IP_HDR_LEN);
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if (err < 0)
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goto out;
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if (!skb_partial_csum_set(skb, off,
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offsetof(struct udphdr, check))) {
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err = -EPROTO;
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goto out;
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}
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if (recalculate)
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udp_hdr(skb)->check =
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~csum_tcpudp_magic(ip_hdr(skb)->saddr,
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ip_hdr(skb)->daddr,
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skb->len - off,
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IPPROTO_UDP, 0);
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break;
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default:
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goto out;
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}
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err = 0;
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out:
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return err;
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}
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/* This value should be large enough to cover a tagged ethernet header plus
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* an IPv6 header, all options, and a maximal TCP or UDP header.
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*/
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#define MAX_IPV6_HDR_LEN 256
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#define OPT_HDR(type, skb, off) \
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(type *)(skb_network_header(skb) + (off))
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static int skb_checksum_setup_ipv6(struct sk_buff *skb, bool recalculate)
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{
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int err;
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u8 nexthdr;
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unsigned int off;
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unsigned int len;
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bool fragment;
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bool done;
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fragment = false;
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done = false;
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off = sizeof(struct ipv6hdr);
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err = skb_maybe_pull_tail(skb, off, MAX_IPV6_HDR_LEN);
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if (err < 0)
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goto out;
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nexthdr = ipv6_hdr(skb)->nexthdr;
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len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
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while (off <= len && !done) {
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switch (nexthdr) {
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case IPPROTO_DSTOPTS:
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case IPPROTO_HOPOPTS:
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case IPPROTO_ROUTING: {
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struct ipv6_opt_hdr *hp;
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err = skb_maybe_pull_tail(skb,
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off +
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sizeof(struct ipv6_opt_hdr),
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MAX_IPV6_HDR_LEN);
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if (err < 0)
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goto out;
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hp = OPT_HDR(struct ipv6_opt_hdr, skb, off);
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nexthdr = hp->nexthdr;
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off += ipv6_optlen(hp);
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break;
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}
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case IPPROTO_AH: {
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struct ip_auth_hdr *hp;
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err = skb_maybe_pull_tail(skb,
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off +
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sizeof(struct ip_auth_hdr),
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MAX_IPV6_HDR_LEN);
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if (err < 0)
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goto out;
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hp = OPT_HDR(struct ip_auth_hdr, skb, off);
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nexthdr = hp->nexthdr;
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off += ipv6_authlen(hp);
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break;
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}
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case IPPROTO_FRAGMENT: {
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struct frag_hdr *hp;
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err = skb_maybe_pull_tail(skb,
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off +
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sizeof(struct frag_hdr),
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MAX_IPV6_HDR_LEN);
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if (err < 0)
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goto out;
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hp = OPT_HDR(struct frag_hdr, skb, off);
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if (hp->frag_off & htons(IP6_OFFSET | IP6_MF))
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fragment = true;
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nexthdr = hp->nexthdr;
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off += sizeof(struct frag_hdr);
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break;
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}
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default:
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done = true;
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break;
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}
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}
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err = -EPROTO;
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if (!done || fragment)
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goto out;
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switch (nexthdr) {
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case IPPROTO_TCP:
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err = skb_maybe_pull_tail(skb,
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off + sizeof(struct tcphdr),
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MAX_IPV6_HDR_LEN);
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if (err < 0)
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goto out;
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if (!skb_partial_csum_set(skb, off,
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offsetof(struct tcphdr, check))) {
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err = -EPROTO;
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goto out;
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}
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if (recalculate)
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tcp_hdr(skb)->check =
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~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
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&ipv6_hdr(skb)->daddr,
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skb->len - off,
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IPPROTO_TCP, 0);
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break;
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case IPPROTO_UDP:
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err = skb_maybe_pull_tail(skb,
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off + sizeof(struct udphdr),
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MAX_IPV6_HDR_LEN);
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if (err < 0)
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goto out;
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if (!skb_partial_csum_set(skb, off,
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offsetof(struct udphdr, check))) {
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err = -EPROTO;
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goto out;
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}
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if (recalculate)
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udp_hdr(skb)->check =
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~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
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&ipv6_hdr(skb)->daddr,
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skb->len - off,
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IPPROTO_UDP, 0);
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break;
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default:
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goto out;
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}
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err = 0;
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out:
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return err;
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}
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/**
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* skb_checksum_setup - set up partial checksum offset
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* @skb: the skb to set up
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* @recalculate: if true the pseudo-header checksum will be recalculated
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*/
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int skb_checksum_setup(struct sk_buff *skb, bool recalculate)
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{
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int err;
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switch (skb->protocol) {
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case htons(ETH_P_IP):
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err = skb_checksum_setup_ip(skb, recalculate);
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break;
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case htons(ETH_P_IPV6):
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err = skb_checksum_setup_ipv6(skb, recalculate);
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break;
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default:
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err = -EPROTO;
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break;
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}
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return err;
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}
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EXPORT_SYMBOL(skb_checksum_setup);
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void __skb_warn_lro_forwarding(const struct sk_buff *skb)
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{
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net_warn_ratelimited("%s: received packets cannot be forwarded while LRO is enabled\n",
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